Q: Can you talk briefly about how much traffic on GERAN you see from iPhone customers? How much of a catch-22 is that situation for moving that PCS spectrum dedicated to it over to WCDMA?

A: We have about a million iphones on our network now. 99.9% of their traffic is 2G/EDGE only right now, so obviously their load is dwarfed by everything else. The iphone is a significant part of the modernization project. Once implemented, iphones will work on U1900 at much higher speeds.

Spectrum is always a limitation. With the software that exists now, you will not be able to do dual carrier split between AWS and PCS. That’s supposed to be fixed in the future, but I don’t know a timeline on it.

Q: Are the upgrades targeting 2G areas first or current 3G/4G areas first? I’ve always figured it would be more sensible to upgrade the 2G-only areas first to get the network fully upgraded.

A: Upgrades are focusing on the core metro areas, very similar to the areas that recieved 3G/4G first…I would love to expand the 4G coverage area, but that’s not happening at the moment.

A confirmation that T-Mobile will roll out 5MHz FDD-LTE when the network is launched, opposed to Verizon’s and AT&T’s 10 MHz FDD, also appeared in the engineer’s responses:

We’re going with remote radios as much as we can, for LTE, UMTS, and GSM….LTE willlaunch with a single 10 MHz channel, 5 up, 5 down.

We will update you here if any other interesting questions/answers pop up on the engineer’s AMA.